Core A, the 'Union Army Sample Maintenance and Improvement Core,' is designed to continue to provide high-quality database management and support to the subprojects described in this proposal, as well as to outside researchers. Core A has the following specific goals. First, we intend to maintain the Union Army lifecycle database as a research tool. Maintenance will consist of purchasing adequate computer equipment to store and disseminate the data through both the Center for Population Economics (CPE) in Chicago and the National Bureau of Economic Research (NBER) in Boston, along with employing personnel to manage it. Second, we propose to improve the database for usability and coverage. The planned improvements to the lifecycle datasets can be summarized in five broad categories: Correcting inconsistencies and errors Coding existing variables Creating additional derived variables Adding information from related sources, to fill in gaps and extend the datasets Improving integration between life-cycle datasets and ecological variables By continuing to provide access to the life-cycle datasets, as well as by improving their usability, we will make it possible for the life-cycle datasets to serve as the basis for a variety of crucial projects related to aging, work levels, and health for years to come.